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Major resistance genes and their chromosome locations, and the wheat varieties and Mycosphaerella graminicola isolates used to map them.
Source publication
This Mycosphaerella graminicola pathogen profile covers recent advances in the knowledge of this ascomycete fungus and of the disease it causes, septoria tritici blotch of wheat. Research on this pathogen has accelerated since publication of a previous pathogen profile in this journal in 2002. Septoria tritici blotch continues to have high economic...
Contexts in source publication
Context 1
... major genes in wheat for resistance to STB have so far been identified and mapped (see Table 2), Stb1-Stb12 and Stb15, but the resistance mechanisms by which these genes confer resistance to specific pathogen genotypes are currently unknown and none of the Stb genes have been cloned. A genefor-gene relationship has been demonstrated between wheat Stb6, the best understood of these genes, and M. graminicola (Brading et al., 2002). ...Context 2
... major genes in wheat for resistance to STB have so far been identified and mapped (see Table 2), Stb1-Stb12 and Stb15, but the resistance mechanisms by which these genes confer resistance to specific pathogen genotypes are currently unknown and none of the Stb genes have been cloned. A genefor-gene relationship has been demonstrated between wheat Stb6, the best understood of these genes, and M. graminicola (Brading et al., 2002). ...Similar publications
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Citations
... B. graminis is of particular importance due to its central and persistent role as the causative agent of disease in cereal crops great significance and as a model for studying other mildew infections (Murray and Brennan 2010). One of the major economic constraints on the productivity of wheat especially in the temperate regions of the world is Mycosphaerella graminicola which causes STB (Septoria tritici blotch) disease (Orton et al. 2011). Infection is marked by hyphal extension on the surface of leaves and via stomatal penetration without appressorium formation (Kema 1996). ...
Agriculture is a prime necessity at this given point in time. Fifty percent of global activities revolve around agriculture. Studies from the Food and Agriculture Organization (FAO) show that 20–40% of crops are destroyed globally due to pests. They are known to cause a major loss to the economy leading to global poverty. Fungal pestilence among them is a burning issue as 85% of plant diseases are caused by fungi. They are a source of biotic stress in plants. Biotic stress includes any live flora or fauna that is known to be pathogenic to plants. To counteract the effects of such pathogenic fungi, plants tend to neutralize the pestilence effect through plant secondary metabolites or polyphenols. Polyphenols or phenolic substances can be explained as the naturally occurring chemical compounds in plants that succor them from biotic and abiotic stress. They have formed from the amalgamation of shikimate; phenylpropanoids; and flavonoid pathways. These derivatives can nurture and endorse many developmental aspects of the plant uniquely counteracting the stress constraints simultaneously. Most polyphenols play a key role as antioxidants against oxidative stress inducers. Hampering the biotic stress restraints using these secondary phytochemicals has been a major milestone in the respective field of plant biology. In this book chapter, we weighed up the pros and cons of the thwarting response of plant-derived polyphenols to the fungal stress constraints, furthermore providing insight into the biosynthesis and biochemistry of the phenolic compounds, their counteract mechanism against fungal toxins, and the aftermath of fungal pestilence on crops and in vitro in a long run.
... Septoria tritici blotch (STB), caused by the ascomycete fungus Mycosphaerella graminicola (Fuckel) J. Schröt. in Cohn (anamorph: Zymoseptoria tritici Roberge in Desmaz.), is a major and persistent threat to wheat cultivation in temperate regions [1,2]. It is considered as the most prevalent and yield-reducing disease in Europe [3], causing up to 50% yield losses under conditions favorable for disease development [4]. ...
... The authors declare that they have no competing interests. 1 ...
Background
Investigations on plant-pathogen interactions require quantitative, accurate, and rapid phenotyping of crop diseases. However, visual assessment of disease symptoms is preferred over available numerical tools due to transferability challenges. These assessments are laborious, time-consuming, require expertise, and are rater dependent. More recently, deep learning has produced interesting results for evaluating plant diseases. Nevertheless, it has yet to be used to quantify the severity of Septoria tritici blotch (STB) caused by Zymoseptoria tritici—a frequently occurring and damaging disease on wheat crops.
Results
We developed an image analysis script in Python, called SeptoSympto. This script uses deep learning models based on the U-Net and YOLO architectures to quantify necrosis and pycnidia on detached, flattened and scanned leaves of wheat seedlings. Datasets of different sizes (containing 50, 100, 200, and 300 leaves) were annotated to train Convolutional Neural Networks models. Five different datasets were tested to develop a robust tool for the accurate analysis of STB symptoms and facilitate its transferability. The results show that (i) the amount of annotated data does not influence the performances of models, (ii) the outputs of SeptoSympto are highly correlated with those of the experts, with a similar magnitude to the correlations between experts, and (iii) the accuracy of SeptoSympto allows precise and rapid quantification of necrosis and pycnidia on both durum and bread wheat leaves inoculated with different strains of the pathogen, scanned with different scanners and grown under different conditions.
Conclusions
SeptoSympto takes the same amount of time as a visual assessment to evaluate STB symptoms. However, unlike visual assessments, it allows for data to be stored and evaluated by experts and non-experts in a more accurate and unbiased manner. The methods used in SeptoSympto make it a transferable, highly accurate, computationally inexpensive, easy-to-use, and adaptable tool. This study demonstrates the potential of using deep learning to assess complex plant disease symptoms such as STB.
... The ascomycete fungus Zymoseptoria tritici, also known as Mycosphaerella graminicola, is responsible for the most economically damaging foliar disease of wheat, called septoria tritici blotch, which is currently affecting wheat production in countries having temperate climates (Orton et al. 2011). Z. tritici has numerous traits that are typical of fungus-based plant diseases, such as a mixed reproductive system and the ability to produce enormous numbers of spores. ...
To better understand the structure and evolution of the genomes of four plant pathogenic species of Zymoseptoria, we analyzed the occurrence, relative abundance (RA), and density (RD) of simple sequence repeats (SSRs) in their whole genome and transcriptome sequences. In this study, SSRs are defined as repeats of more than 12 bases in length. The genome and transcriptome sequences of Zymoseptoria ardabiliae show the highest RA (201.1 and 129.9) and RD (3229.4 and 1928.2) of SSRs, while those of Zymoseptoria pseudotritici show the lowest RA (167.2 and 118.5) and RD (2482.2 and 1687.0). The majority of SSRs in the genomic and transcriptome sequences of species were trinucleotide SSRs, while dinucleotide SSRs were the least common. The most common trinucleotide motifs in the transcriptomic sequences across all species were those that encoded the amino acid arginine. As per our motif conservation study, Zymoseptoria tritici (12.4%) possessed the most unique motifs, while Z. pseudotritici (3.9%) had the fewest. Overall, only 38.1% of the motifs were found to be conserved among the species. Gene enrichment studies reveal that three of the species, Z. ardabiliae, Zymoseptoria brevis, and Z. pseudotritici, have SSRs in their genes related to cellular metabolism, while the remaining Z. tritici harbors SSRs in genes related to DNA synthesis and gene expression. In an effort to improve the genetic resources for the orphan species of pathogenic Zymoseptoria, a total of 73,134 primers were created. The genomic resources developed in this study could help with analyses of genetic relatedness within the population and the development of species-specific markers.
... Moreover, for specific interactions between wheat cultivars and Z. tritici isolates, 22 Lb genes have been observed (Brading et al. 2002;Goodwin 2007;Ghaffary 2011;Orton et al. 2011;Brown et al. 2015). The gene Lb6 encodes wall-associated kinases that confer gene-gene mechanisms of resistance . ...
... Of them, Z. ardabiliae and Z. pseudotritici have been isolated from Elymus repens, Dactylis glomerata, and Lolium perenne in Iran (Stukenbrock et al. 2012). As a heterothallic ascomycete, the teleomorph of Z. tritici is Mycosphaerella graminicola (Hunter et al. 1999;Linde et al. 2002;Zhan et al. 2003;Orton et al. 2011). ...
... Under this review, my target is Z. tritici species. Mycosphaerella graminicola (Fuckel) (anamorph: S. tritici Roberge in Desmaz.) is the sexual form and is a species of filamentous fungus that belongs to kingdom Mycota, Phylum of Ascomycota, Class Dothideomycetes, in the family of Dothideaceae, Genus Mycosphaerella, Species graminicola (Orton et al. 2011). ...
Septoria tritici blotch or Septoria leaf blotch has been used for long time, but leaf blotch is a correct disease name. Moreover, Lb resistant gene is the correct name, but, not Stb gene. It has sexual and asexual parts on the mycelia, known as heterothallic fungi. Its pathogenic diversity ranged from 40% to 93% and has produced a wide variety of AvrLb6 haplotypes. M. graminicola has a plasmogamy and karyogamy sexual process. The pathogen can use macropycnidiospores, micropycnidiospores, and pycnidia vegetative growths for infection and overwintering. Synthetic M3, Kavkaz-K4500, Synthetic 6×, and TE9111 wheat genotypes have horizontal resistance. Avirulence (Avr) genes in Z. tritici and their matching wheat (R) genes indicate gene for gene mechanisms of resistance. Twenty-two R genes (vertical resistance) have been identified. In both horizontal and vertical resistance, different Lb genes have been broken down due to new Z.tritici virulent gene and currently Lb19 resistant gene is being recommended. Mixing of resistant and susceptible cultivars is also the most effective management strategy. Moreover, different cultural practices and biological control have been proposed. Lastly, different fungicides are also available. However, in developing countries cultivar mixture, isolates diversity, biological control, and epidemic studies have been greatly missed.
... Members of this species are well characterized regarding their pathogenic character. This pathogen is spread by wind, and its propagation is ensured by both sexual ascospores and asexual pycnidiospores [280]. ...
Besides plants and animals, the Fungi kingdom describes several species characterized by various forms and applications. They can be found in all habitats and play an essential role in the excellent functioning of the ecosystem, for example, as decomposers of plant material for the cycling of carbon and nutrients or as symbionts of plants. Furthermore, fungi have been used in many sectors for centuries, from producing food, beverages, and medications. Recently, they have gained significant recognition for protecting the environment, agriculture, and several industrial applications. The current article intends to review the beneficial roles of fungi used for a vast range of applications , such as the production of several enzymes and pigments, applications regarding food and pharmaceutical industries, the environment, and research domains, as well as the negative impacts of fungi (secondary metabolites production, etiological agents of diseases in plants, animals, and humans, as well as deteriogenic agents).
... Hemibiotrophic pathogens are characterized as having a biotrophic phase during primary infection and a necrotrophic phase, in which enzymes are secreted to degrade host cell walls, together with a build-up of mycotoxins (Goswami and Kistler, 2004;Kazan et al., 2012;Castiblanco et al., 2018). The Ascomycota Mycosphaerella graminicola (anamorph Zymoseptoria tritici) causes one of the most economically devastating foliar diseases of wheat in Europe, namely septoria leaf blotch (Orton et al., 2011). Temperate climates and rain-fed environments favor the development of this disease. ...
Conventional chemical crop protection with pesticides is increasingly seen as being critical, because of pesticide residues in food and the environment. Integrated alternative management strategies such as crop rotations and soil management might also involve the targeted use of certain mineral fertilizers with benefits for plant health. A key element required for healthy crops is nitrogen, which is applied at differing dosages in various chemical forms, all with distinct effects on crop physiology and plant growth. Here, we review classical and more recent evidence for the crop disease-protective effects of nitrogen and various chemical nitrogen forms. We conclude that simple general statements concerning disease-protective roles in agricultural environments remain elusive, although complex plant-soil microbial interaction networks are becoming increasingly understood. The health of modern varieties might be substantially improved by certain chemical nitrogen fertilizer forms, particularly when the disease-causing fungal species are known.
... Both barley scald and wheat leaf blotch are similar at the species level (graminicola), but they are different at the genus level (Rhynchosporium for barley scald and Mycosphaerella for wheat leaf blotch). At the phylum level, both diseases belong to the Ascomycota class [18,46]. Since their modes of infection and spore production are identical, barley scald can be managed by using cultural practice in the same ways as wheat leaf blotch. ...
Barley scald is very important in temperate and wet regions worldwide and has become one of the most important foliar diseases. Before the development of recent technologies, several scientists had argued that Rhynchosporium secalis is the causal agent of scald disease. However, the causal agent of this disease was revised and recognized as Rhynchosporium commune. Again recently, Rhynchosporium graminicola was suggested to be replaced as the causal agent of R. commune. The disease outbreak is depending on cool and frequent rainfall. Because of scald disease significance, numerous management practices have been advocated. Then, resistance materials, and mixing of resistant and susceptible cultivars have been used as the best management methods. Several studies have demonstrated that some cultivars and landraces of barley are resistant to scald disease during the seedling and adult growth stages. The first cultivar is “Atlas 46″ which was created from the cultivar “Turk”. From biological method: Bacillus polymyxa, Paenibacillus polymyxa KaI245, and Bacillus subtilis are very effective in treating this disease. Finally, as a last option, different fungicides have been suggested. Pathogenicity testing, seed treatments, tillage, cultivar mixtures, and biological control are all commonly overlooked in developing countries. Cultural practices such as times of fungicide application, appropriate time of sowing to scape disease, and tillage practices which are adopted for other diseases are greatly missed for scald disease. Then, we are intended to assess the various findings available on barley scald biology, taxonomy, and management.
... Septoria tritici blotch STB (caused by Zymoseptoria tritici) (Oerke, 2006;Dean et al., 2012;Torriani et al., 2015). STB is the most important foliar disease of winter wheat in Europe as it accounts for 5-10% of annual yield losses, while a further €1 billion is spent by farmers across Europe on fungicides to control STB (Orton et al., 2011;Fones & Gurr, 2015;Torriani et al., 2015). The emergence and dispersal of fungicide resistance in fungal populations severely threatens wheat production and compromises food security (Torriani et al., 2009;Cools & Fraaije, 2013;Estep et al., 2015). ...
... The asexual reproductive cycle allows Z. tritici to rapidly evolve new fitness traits such as fungicide resistant genotypes, while the sexual reproduction allows for rapid gene flow to facilitate the spread of such traits over large geographical areas (Orton et al., 2011;Fisher et al., 2012). This heterothallic nature makes Z. tritici a highly challenging pathogen in terms of durable disease control (Fisher et al., 2012;Talbot, 2015). ...
Zymoseptoria tritici, a fungal pathogen of wheat and the causal agent of Septoria Tritici Blotch (STB), is a particular challenge to wheat production on a global level, causing severe crop losses. As the site of photosynthesis, the chloroplast plays a crucial role in energy balance and trade-off between growth demands and response to environmental stresses and it is gaining an ever-growing attention due to its multilayered involvement in disease response and downstream signalling. However, very little is known regarding wheat resistance responses to Z. tritici and the involvement of chloroplastic photoprotection. In the following thesis, I present data indicating the importance of photoprotection, through non-photochemical quenching (NPQ), in disease resistance of wheat plants against virulent and avirulent Z. tritici isolates. This study presents novel data on wheat plants with increased, “primed” photoprotection resulting in enhanced tolerance towards virulent and avirulent isolates. Plants were over-expressing the photoprotective chloroplastic protein PsbS and maintained a greener phenotype and reduced pycnidia upon inoculation with virulent strains of Z. tritici. Stb6, which encodes a wall-associated kinase protein that confers resistance to Z. tritici isolates expressing the corresponding AvrStb6 effector, has recently been cloned. In this study, I also used Stb6 near-isogenic lines and present findings on the association between the photoinhibitory component of NPQ, qI, and the avirulent isolate IPO323, at 24 hours after inoculation. Transcriptomic analysis also revealed the importance of the oxygen-evolving complex and photosystem II antenna proteins in resistance responses. In contrast, avirulent Z. tritici had no effect on photoprotection; however results indicated a potential virulent strategy that exploits the photosynthetic repair machinery. Also, this study presents early findings on interactions and potential mechanisms of effector-triggered susceptibility from Z. tritici, utilising necrotrophic effectors from another foliar wheat pathogen, Parastagonospora nodorum. This study represents an important contribution to our understanding of chloroplastic responses to the important pathogen Z. tritici and suggests putative mechanisms of photoprotective, chloroplastic defence. Understanding and incorporating chloroplastic mechanisms into breeding programs could help develop more productive crop plants with a novel durable genetic resistance to plant pathogens.
... En el trigo se pueden encontrar dos tipos de resistencia a Z. tritici. La resistencia cualitativa (monogénica o vertical) y la resistencia cuantitativa (poligénica, horizontal o parcial) (Orton et al., 2011;Dreisigacker et al., 2015). En la última década se han identificado 21 genes (Stb) que confieren resistencia cualitativa y 167 loci para un carácter cuantitativo, por sus siglas en inglés (QTL) en 19 poblaciones biparentales de mapeo, que otorgan resistencia cuantitativa (Gurung et al., 2014;Brown et al., 2015). ...
La mancha foliar del trigo causada por Zymoseptoria tritici es una enfermedad devastadora en el cultivo de trigo a nivel internacional. El control químico y el uso de variedades resistentes son las principales estrategias de control. El Centro Internacional de Mejoramiento de Maíz y Trigo (CIMMYT), cuenta con líneas de trigo con resistencia cuantitativa a la enfermedad por lo que el objetivo fue hacer un mapeo de loci para un carácter cuantitativo (QTL) asociados con la resistencia genética a la mancha foliar en la línea élite Mutus#1 (resistente), en una población de 275 líneas endogámicas recombinantes (LER) derivadas de la cruza de Mutus#1 con la línea élite Huirivis#1 (susceptible). En 2018 y 2019, en la estación del CIMMYT-Toluca se estableció un experimento en campo bajo un diseño experimental Alpha Lattice. Se generó una epidemia artificial con Z. tritici y se calculó el área bajo la curva del progreso de la enfermedad (ABCPE). Las 275 LER y los progenitores se secuenciaron utilizando la plataforma DArTSeq. Los mapas de ligamiento se construyeron con el programa IciMapping empleando la información del fenotipo y genotipo. Se identificaron cinco QTL de efecto menor, tres ubicados en los cromosomas 1B, 4A y 4B y dos en el cromosoma 5B, los cuales explicaron menos de síntomas y producción de picnidios en planta adulta portados por Mutus#1, pueden utilizarse con otros genes de resistencia o QTL para reducir la selección de nuevas cepas patogénicas de Z. tritici.
... Brown-black fruiting bodies (pycnidia) emerge on the surface of these foliar necrotrophic patches, ready to spread the spores. The necrotic patches observed over leaves decrease plants' overall photosynthetic capabilities, which translate directly to a reduction of the yield [8,9]. ...
Background
Wheat is one of the most important staple crops produced worldwide. Its susceptibility to plant diseases reduces its production significantly. One of the most important diseases of wheat is septoria tritici blotch, a devastating disease observed in fields with wet and temperate conditions. Z. tritici secretes effector proteins to influence the host’s defense mechanisms, as is typical of plant pathogens. In this investigation, we evaluated the pathogenicity of some Zymoseptoria tritici effector candidate genes having a signal peptide for secretion with no known function.
Methods and results
Three genes named Mycgr3G104383, Mycgr3G104444 and Mycgr3G105826 were knocked out separately through homologous recombination, generating Z. tritici IPO323 mutants lacking the functional copy of the corresponding genes. While KO1 and KO3 mutants did not show any significant differences during phenotypic and virulence investigations, the KO2 mutant generated exclusively macropycnidiospores in artificial media, different from wild-type IPO323 which produce only micropycidiospores. The mycelial growth capability of KO2 was also severely attenuated in all of the investigated growth conditions. These changes were observed independent of growth media and growth temperatures, implying that changes were genetic and inherited through generations. Virulence of knockout mutants in wheat leaves was observed to be similar to the wild-type IPO323.
Conclusion
Understanding the biology of Z. tritici and its interactions with wheat will reveal new strategies to fight septoria tritici blotch, enabling breeding wheat cultivars resistant to a broader spectrum of Z. tritici strains. Furthermore, gene knockout via homologous recombination proved to be a powerful tool for discovering novel gene functions.
